1. Field of the Invention
The present invention relates to a motor controller for controlling a motor and an image forming apparatus employing the motor controller.
2. Description of the Related Art
Available as a drive power source for a diversity of apparatuses is a motor such as a DC motor, a stepping motor, an AC motor, a vibration wave (ultrasonic) motor, and the like. As disclosed in Japanese Patent Laid-Open No. 58-14682, Japanese Patent Laid-Open No. 63-1379, Japanese Patent Laid-Open No. 60-176470, and Japanese Patent Laid-Open No. 59-204477, a vibration wave motor is composed of an electrical-to-mechanical energy converting vibrator which vibrates in response to a high frequency voltage (drive signal) applied thereto, and a contact member in contact with the vibrator. The contact member is frictionally driven relative to the vibrator by the mechanical vibration energy of the vibrator.
The vibration wave motor features an excellent low-speed rotation reliability, eliminating the need for gear reduction and permitting low noise operation. The vibration wave motor is useful in copying apparatuses and printers, for which low-vibration and low-noise operation is typically required. The vibration wave motor is particularly useful for the precision control of a photoconductive member and a transfer member, which directly affect the image quality in the copying apparatus and the printer.
To control the vibration wave motor in the copying apparatus or the printer, the supplying of a drive signal to the vibration wave motor is started to operate the photoconductive member or the transfer member at the start of a print job, and is halted to stop the operation of the photoconductive member or the transfer member at the end of the print job or at an irregular stop such as the occurrence of a paper jam.
When no drive signal is input to the vibration wave motor, the vibration wave motor stays motionless and cannot be moved. Even if an attempt is made to manually rotate the photoconductive member or the transfer member to remove a residual paper sheet in the apparatus at the occurrence of a paper jam or an error, the vibration wave motor stays motionless, and removal of a residual paper sheet is thus difficult.
Service engineers cannot manually rotate the photoconductive member or the transfer member in the apparatus during maintenance.
An object of the present invention is to provide a motor controller and an image forming apparatus employing the motor controller, which permit a photoconductive member or a transfer member to be manually rotated while a drive signal is still unable to start the rotation of a halted vibration wave motor.
It is another object of the present invention to provide a motor controller which inputs a drive signal that has characteristics that do not permit a vibration wave motor to rotate on its own subsequent to the event of an irregular stop.
It is yet another object of the present invention to provide a motor controller which inputs a drive signal that has characteristics that selectively do not permit vibration wave motors to rotate on their own.
According to one aspect of the present invention, a controller for controlling a vibration wave motor which applies a frequency signal to an electrical-to-mechanical energy converting element mounted on a vibrator to produce driving power, includes a signal forming circuit for forming the frequency signal, and a mode setting circuit for setting a first mode in which a frequency or voltage required for normal driving is set as the frequency signal, and a second mode in which a frequency or voltage unable to start rotation of the motor but still permitting the motor to be manually rotated is set as the frequency signal.
According to another aspect of the present invention, a controller for controlling a plurality of vibration wave motors, each motor applying a frequency signal to an electrical-to-mechanical energy converting element mounted on a vibrator to produce driving power, includes a signal forming circuit for forming the frequency signal, a mode setting circuit for setting a first mode in which a frequency or voltage required for normal driving is set as the frequency signal, and a second mode in which a frequency or voltage unable to start rotation of the motor but still permitting the motor to be manually rotated is set as the frequency signal, and a selecting circuit for selectively applying the frequency signal in the second mode to the motor.
According to yet another aspect of the present invention, an image forming apparatus employing, as a drive power source, a vibration wave motor which applies a frequency signal to an electrical-to-mechanical energy converting element mounted on a vibrator to produce driving power, includes a signal forming circuit for forming the frequency signal, and a mode setting circuit for setting a first mode in which a frequency or voltage required for normal driving is set as the frequency signal, and a second mode in which a frequency or voltage unable to start the rotation of the motor but still permitting the motor to be manually rotated is set as the frequency signal.
According to yet another aspect of the present invention, an image forming apparatus employing, as drive power sources, a plurality of vibration wave motors, each motor applying a frequency signal to an electrical-to-mechanical energy converting element mounted on a vibrator to produce driving power, includes a signal forming circuit for forming the frequency signal, a mode setting circuit for setting a first mode in which a frequency or voltage required for normal driving is set as the frequency signal, and a second mode in which a frequency or voltage unable to start the rotation of the motor but still permitting the motor to be manually rotated is set as the frequency signal, and a selecting circuit for selectively applying the frequency signal in the second mode to the motor.
These and other objects of the present invention will be apparent from the following discussion of the embodiments.